As electronic devices, such as personal digital assistants (PDAs), cellular phones and other hand held electronic devices continue to decrease in size, proper design of the input interface for these devices becomes more important. As the space required for implementing the input interface becomes increasingly more limited, an improper design of this interface may render the electronic devices cumbersome, slow, or even unusable. For example, too many buttons on the interface may disorient an unsophisticated user. Too few keys may require that the available buttons be assigned secondary or even tertiary functions, greatly increasing the number of keystrokes and time required for even simple entries. A cumbersome layout would render the data entry slow and tedious, while tiny keys or buttons would be difficult to see and manipulate and, in addition, would require extreme precision on the part of the user.
Current hand held electronic devices have mitigated these problems by incorporating a scheme that allows menu and other selections to be made by touching sensitive areas of the screen. In addition, many devices allow alphanumeric character input by means of a stylus that is used to “write” on a touch-sensitive portion of the screen. The electronic device is then capable of translating the handwriting using a simplified handwriting-recognition algorithm. While this method is improved, it is still necessary for the user to use two hands to enter the data, one hand to hold the apparatus and one hand to write on the screen. Additionally, the apparatus must interpret the handwriting into a computer readable format, and the procedure for doing so is time consuming and is also less than 100% accurate. Furthermore, the variety of characters that may be entered may be limited based on the ability of the apparatus to discern between various handwritten material.
Other hand held electronic devices allow the user to input data while still maintaining a reduced overall size by providing a keyboard for data entry, which is implemented as a graphic on a liquid crystal display (LCD). Thus, the LCD displays a keyboard, such as would be available in a regular computer or typewriter, and the user touches each of the LCD-displayed keys to enter data. However, even these keyboards may be insufficient, since if the apparatus is small enough, the keyboard keys are so small so as to be difficult to use by the user. Additionally, if the graphical display is too small, such a keyboard will not function properly.
The aforementioned interfaces, while functional, do not represent an optimal solution that adequately addresses the rapid input of alphanumeric and other data input in some electronic devices.
Accordingly, the need for such an input interface has heretofore remained unsatisfied.